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Fasting during Yom Kippur (Day of Atonement) and Tisha B’Av (9th of
Av)
Reviewed October 2011
Page 1 of 2
Yom Kippur (Day of Atonement) and Tisha B’Av (9th day of Av) are special 25-hour fasts for
Jewish people.
What are the dangers of fasting?
For people with diabetes taking certain tablets and/or insulin to manage their condition, the
greatest danger is that of hypoglycaemia.
It is also possible that people could develop high blood glucose levels during a fast if they omit
their medication, or if they are less physically active than normal.
If you are intending to fast you should attend your diabetes clinic for an assessment of your
current level of diabetes control. Your healthcare team should discuss with you any difficulties
experienced in previous fasts and how you coped with them. They can advise on any adjustment
of medication that may be required to enable you to fast safely.
To reduce the possibility of becoming hypoglycaemic (hypo) you should rest as much as
possible during the fast. If you are fasting and feel hypoglycaemic you must take some sugary
fluids and follow it with starchy food. This breaking of the fast is permitted since Jewish law
states a person should not put their health at risk and becoming hypoglycaemic could do just that.
There is also the danger of the blood glucose level becoming too high when normal levels of
medication are not taken. This can lead to diabetic ketoacidosis (DKA), a condition requiring
hospital admission. The symptoms of DKA include feeling very thirsty and passing a lot of
urine. If someone is fasting and does not take in fluids to reduce their thirst, this will accelerate
dehydration and they will require urgent admission to hospital.
Changes to diet
The body is used to having regular amounts of food throughout the day. When fasting people
often have larger meals either side of the fast. The type of food eaten should be considered. It is
important not to forget the principles of healthy eating which should be applied to your regular
daily intake. This does not mean you cannot enjoy special foods prepared at this time, rather you
should consider the quantities eaten and choose healthy options where applicable, eg take sugarfree drinks and eat plenty of fruit and vegetables. Some people with diabetes will also make sure
they take less salt prior to fasting in order to reduce the effects of dehydration.
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Yom Kippur and Tisha B’Av
Page 2 of 2
People whose diabetes is controlled by diet and physical activity alone should be able to fast but
this should be discussed with your healthcare team. This is especially important before Yom
Kippur and Tisha B’Av, as these are prolonged periods of fasting and could cause blood glucose
levels to rise even though you are not eating.
Changes to treatment
The body will have difficulties maintaining adequate blood glucose levels during the period of
fasting, so adjustments need to be made to any prescribed medication.
If you are taking insulin it is important that your control is good before you consider fasting.
Your healthcare team may advise against fasting if you have poor control or if there is evidence
of complications due to diabetes. You will require less insulin before the start of the fast, and the
type of insulin may also need changing from your usual type. Pre-mixed insulin is not
recommended for people who are intending to fast. Due to the dangers of omitting insulin for 25
hours, you may be advised not to fast for this length of time. Your healthcare team should advise
on what is best for you.
If you take tablets to control your blood glucose it may be possible to alter the time and/or dose
during the fast. This will depend on the type of medication you are taking. Your doctor might
suggest changing to an alternative tablet in order to prevent large variations in blood glucose
levels whilst fasting. It is not recommended that tablets be omitted for the full 25 hours due to
the danger of raised blood glucose levels. You need to discuss this with your healthcare team.
Other factors to consider
If there is evidence of any damage to your eyes, kidneys, heart or the nerves in your hands and
feet, it would not be advisable for you to fast. You must talk to your healthcare team about this
as they will know the extent of any existing damage due to high blood glucose levels, and will be
able to advise on the risk of further damage if you follow the fast.
Many people with diabetes on tablets or insulin would not be medically advised to fast for the
longer periods and, if this is the case for you, this should be discussed with your rabbi in order to
obtain permission not to fast. If medication is recommended during the fast, this should also be
discussed with your rabbi.
Careline Information Team
© Diabetes UK 2011